What's the best place to add SEO keywords for a preloved fashion site?

[LouSells]

Evening,

I am look for some help on best location to add keywords to the main part of my site. My products change regularly as we only stock individual pieces so I need majority of the key words embedded in coding perhaps if possible? I had added as many as I can to the main text and alt images but is there anywhere that would help get us to somewhere near the first page of google?

keywords would be:

preloved clothing

secondhand fashion

preloved designer handbags

preowned clothing

preowned fashion

secondhand womenswear

secondhand clothes